Quintessence International, 06/1991

Restoration of severely damaged teeth requires comprehensive, carefully planned pretreatment. This report of a patient who sustained traumatic injury to the maxillary anterior teeth demonstrates the use of accelerated forced eruption to strengthen damaged roots, allowing placement of crowns and eliminating the need for a fixed partial denture.

The increasing use of oral endoprostheses has offered new alternatives for fixed and removable prosthesis design. However, the use of implants also requires the complex understanding and use of sound prosthodontic principles. The establishment of proper maxillomandibular relationships (vertical dimension, occlusal plane, curve of Spee, tooth arrangement), esthetics, and function are essential precursors to success. Although the usefulness of rehabilitation with overdentures supported by osseointegrated fixtures is sometimes underestimated, overdentures provide an adequate treatment alternative in indicated cases. A case is presented in which previous preprosthetic surgery had failed and subsequently an overdenture supported by osseointegrated fixtures was constructed.

This article describes improvements in retention of resin-bonded, cast metal rest seats that utilize cast pins for additional stabilization and resistance to intraoral forces of dislodgment. This method combines the classic design of pin-ledge retainers with the resin-bonded concept of retention to provide a reliable and stable, but conservative, method of altering tooth form to support removable partial dentures.

Superior labial frena obtained from cadavers or frenectomies were examined histologically. The frena were covered by stratified squamous nonkeratotic, orthokeratotic, or parakeratotic epithelia, depending upon the gingival extent of the frenum. In addition to the normal c omponents of dense, irregular, collagenous connective tissue, almost all frena contained myelinated nerve fiber bundles and small vascular channels. Additionally, 35% of the frena examined contained a few small skeletal muscle fibers.

The clinical yellowing of anterior composite resin restorations with time is often the cause for their replacement. This work examined in vitro the effect of sunlight and water separately and together on color changes in the lighter shades of 16 resins. The natural radiation (ultraviolet and visible) was greater than would be expected in clinical use, and the color changes were generally only slight for most resins, as judged by standardized photographic recording and visual inspection of transparencies over time. The changes were greater when sunlight and water were combined. The light-cured surface was less affected than the distal surface. The hydrolysis action by water was particularly marked for one resin, which also showed a high release of camphoroquinone-type catalyst. Marked clinical discoloration may be as much or more affected by absorption of food colorants than by sunlight and water.

This study was performed in vivo over a 6-month period to assess restorative margins in Class V restorations placed with different techniques. The margins were evaluated quantitatively under the scanning electron microscope using the replica technique. Results indicated that the sandwich technique using a glass-ionomer cement base and a composite resin restoration was not able to prevent marginal gaps in dentin. However, the experimental Gluma/Clearfil system resulted in a quality of dentinal margins not statistically significantly different from that of enamel margins. These in vivo findings substantiate in vitro results.

The bond strength and microleakage patterns of three light-curing glass-ionomer cement liners/bases (Vitrebond, XR Ionomer, and Zionomer) were evaluated and compared to a fluoride-releasing resin (TimeLine) designed for the same use. Bond strength tests were performed at 24 hours and 7 days. At 24 hours Vitrebond, TimeLine, and Zionomer had statistically significantly greater bond strengths than XR Ionomer. At 7 days, Vitrebond had a statistically significantly stronger bond than the others. Microleakage was evaluated after 24 hours of thermocycling. Vitrebond and XR Ionomer had statistically significantly less leakage than the others, while TimeLine had significantly more leakage than the others. Polymerization contraction gaps between the liners/bases and dentin were examined with scanning electron microscopy. Contraction gaps were approximately 10 um with Vitrebond and XR Ionomer and 5 um with TimeLine. A contraction gap generally was not observed with Zionomer.

Interfacial tensile bond strengths of self-cured and light-activated composite resins, repaired with the same or another composite resin, were measured. The bond strengths were measured as a function of age of the substrate or as a function of the adhered surface treatment. One control group of solid resin samples was tested for tensile strength. Other groups of specimens, matured for 48 hours, 7 days, and 1 year, were cut in half an d ground flat before a fresh mass of composite resin was added. Six groups were coated with a thin layer of intermediate resin or bonding aggent before the fresh composite resin was added. In general, the repaired composite resins revealed lower strength than did the cohesive samples, with bond strengths ranging from 19% to 52% of the strengths of the unrepaired resins. The intermediate resin increased the bond strength in all cases.

The interdental pailla is the anatomic site most susceptible to periodontal disease. The gingival epithelium plays an important role as a barrier to protect the underlying connective tissue from exogenous noxious agents. A study was undertaken to evaluate the papillary epithelial response to reconstructive stresses conducted by gingival brushing (oral therapy) and scaling and root planing, intended to induce a keratinization associated with reduction or resolution of connective tissue inflammation. Results showed that patients who prolonged the interproximal hygiene practices for more than 30 minutes a day achieved a satisfactory keratinization of the papillary gingival epithelium.

A clinical technique is presented that allows practitioners to use adhesive bonding techniques to improve the retention and seal of gold castings. At the time of delivery of a gold casting, the preparation is treated with a self-curing enamel and dentinal bonding agent. The internal surface of the casting is sandblasted and electroplated with tin to produce a surface suitable for bonding with a resin cement, which is virtually insoluble and is adhesive to both the metal surface and the treated tooth.

Following deep restorations in vital teeth, postoperative pain of various durations frequently occurs, even if the teeth were asymptomatic before treatment. In this study, a potassium nitrate-polycarboxylate cement was used as a liner and was found clinically to tend to preserve pulpal vitality and significantly eliminate or decrease postoperative pain.